Allen-Bradley 1747-SN Remote I/O Scanner Module

The Allen-Bradley 1747-SN, also cataloged as the 1747-SN Remote I/O Scanner Module, serves as the primary SLC 500 Remote I/O Scanner Module utilized to execute deterministic remote I/O polling and adapter-to-controller data exchange across distributed SLC 500 rack systems. It provides a single RIO port interface for cyclic communication between SLC processors and remote I/O adapters under 5 VDC backplane operation.

Hardware Specifications

Backplane Bus Communication and Remote I/O Deterministic Scan Architecture (Allen-Bradley SLC 500)

The 1747-SN implements a Remote I/O scanning engine integrated into the SLC 500 backplane, consuming 600 mA at 5 VDC to execute cyclic polling between controller memory and distributed I/O adapters. The module translates rack-level scan commands into RIO protocol transactions over a single communication port, maintaining synchronized data mapping between local processor logic and remote chassis assemblies.

The scanner supports Normal Mode and Complementary Mode, extending connection handling from 16 to 32 device links depending on scan configuration. Signal integrity across long-distance cabling (up to 3050 meters) is maintained through noise-immune RIO encoding, allowing stable communication under industrial electromagnetic conditions. The module directly interfaces with SLC 5/02 through 5/05 processors, where scan execution is governed by processor task scheduling and backplane arbitration timing.

Frequently Asked Questions (FAQ)

Q: Can the 1747-SN operate with multiple RIO ports?
A: No. The module is equipped with a single RIO communication port for all remote I/O scanning operations.

Q: What is the difference between Normal Mode and Complementary Mode?
A: Normal Mode supports up to 16 device connections, while Complementary Mode extends addressing capacity to 32 connections within the same RIO scan structure.

Q: Is hot-swapping supported for this module?
A: No. The module must be installed or removed with chassis power removed to prevent backplane corruption and scan interruption.

Field Installation Guidelines

• Install into any compatible SLC 500 rack slot following processor slot rules.

• Ensure stable 5 VDC backplane supply before insertion (600 mA load capacity required).

• Use approved Remote I/O trunk cable with proper termination resistors at both network ends.

• Maintain cable shielding continuity and single-point grounding to reduce noise coupling.

• Verify processor compatibility (SLC 5/02 through 5/05) prior to configuration.

• Confirm operational mode selection (Normal or Complementary) before commissioning scan execution.